Braking mechanism for rotary oil well drilling apparatus



Dec. 20, 1932.

E. .LWLE COMPTE ET AL 1,891,329

Original Filed Feb. 23, 1952 5 Sheets-Sheet l E. J1 560MP r5CIA/714,920.90

Arroemsv Dem 1932- E. J. LE COMPTE ET AL 1,891,329

BRAKING MECHANISM FOR ROTARY OIL WELL DRILLING APPARATUS Original FiledFeb, 23, 1932 SSheets-Sheet 2 1932 4 5 Sheets-Sheet 3 l4 5 o T F n u n7v .9 www E WM? M41. W o 3 5 I J. NM 2 H f. 6 5 U n 57 8 .9 J 8 1 W5 85F 8 I H v E. J. LE COMPTE ET AL Original Filed Fb. 23

1 a E s IIUWII Dec. 20, 1932.

BRAKING MECHANISM FOR ROTARY OIL WELL DRILLING APPARATUS ATTO/E/YEV Dec.20, 1932. E. J. LE CAOMPTE' ET AL 1,891,329

BRAKING MECHANISM FOR ROTARY OIL WELL DRILLING APPARATUS Original FiledFb. 25, 1952 s Sheets-Sheet 4 Arromvsy Dec. 20, 1932. E, J, L: COMPTE ETAL 1,891,329

BRAKING MECHANISM FOR ROTARY OIL WELL DRILLING APPARATUS Original FiledFeb. 25, 1952 5 Sheets-Sheet 5 Patented Dec. 20, 1932 EDWARD J. ancomers Ann cAiarE-a a HARRISSON, OF ST. LOUIS, MISSOURI, AS-

SIGNORSTO NATIONAL OIL DIR-ILL CORPORATION, OF ST. LOUIS, MISSOURI, COR-lPORA'IION OF DELAWARE BRAKING MECHANISM FOR ROTARY OIL WELL DRILLINGAPPARATUS Original application filed February 23, 1932, Serial No.594,540. Divided and this application filed -J'une s, 1932. Serial No.615,088.

Our invention relates to deep oil well drilling apparatus.

In deep oil well drilling, it is a Well known fact to drillers, thatcertain predetermined pressure applied to the drill bits should not beexceeded. This pressure varies according to earth formations, to insurethe highest efliciency. in the cutting of certain earth formations,particularly hard earth formations, such for instance, as granite, orthe like,and it is well understood that greater pressure on the bit thanthat recommended by manufacturer of bits for the various formations,quickly dulls the drill cones and often crushes the same, incurringunnecessary inconvenience and expense to the driller, besidesaggravating the tendency of the bit to cut at an angle to the straighthole desired.

Our invention has for an object, the provision of telescopic meansconnected into the drill stem line at a predetermined section in thelength thereof, which telescopic means is employed in lieu of a certaindrill stem section, and it is provided with means to set up a backpressure of mud laden fluid when partly collapsed, said telescopic meanspermitting a predetermined pressure, gauged by the weight of the drillstem section below the telescopic means, being uninterruptedly appliedto the drill cones, to avoid unnecessary dulling of the bit, avoidpossible crushing of the bit when drilling through hard earth formation,and, in general, thereby facilitate the drilling of an approximatelystraight hole to any depth.

A further object of the invention resides in the provision of meansco-acting with the telescopic drill stem section and actuated by theback pressure of mud laden fluid built up above the telescopic drillstem section to the mud pump, to indicate to the driller, by thelighting of a signal lamp, that the progress of the bit into the earthformation is relatively slower than the feeding of drill stem disposedabove the telescopic drill stem section. 1

. A still further object of the invention, and

' the feature thereof to which this application relates, resides in theprovision of brake actuating mechanism co-acting with the telescopicdrill stem section and actuated by the back pressure of mud laden fluidbetween the telescopic drill stem section and the mud pump forautomatically retarding the lower- ,ing of additional drill stem intothe hole above the telescopic drill stem section, and, if necessary,stop further lowering of drill stem above the telescopic drill stemsection altogether until such time as additional upper and finallypointed out in the claims hereto appended. I

Referring to the accompanying drawings forming a part of thisspecification, wherein like characters of reference denote similar partsthroughout the several views: Figure 1 is a view of a rotary oil welldrilling apparatus including the embodiment of our invention.

Figure 2 is a slightly enlarged view of the drilling apparatus includingthe embodi-.;

ment of our invention, the upper end of the derrick being broken away,and certain parts of the apparatus not being shown, such for instance,as the mud pumpand the steam boiler.

Figure 3 is a sectional view of drill stem section embodying thefeatures of our invention and with part of one of the members thereofbroken away.

, Figure 4 is a view partly in side eleva tion and partly in sectionalelevation, of a string of connected drill stemsand a drilling bit on thelower'end thereof, including our telescopic drillstem section, and shownas in operationin an oil well bore a telescopic with the telescopicdrill stem section in its furthest extended position.

Figure 5 is a view similar to Figure 4, showing the telescopic drillstem section as partly collapsed, which would set up a back pressure ofmud laden fluid suflicient to displa a yellow warning light to thedriller, indicating to him that the drill bit is not entering the earthformation as fast as the drill stem is being lowered from the derrick.

Figure 6 is a view similar to Figures 4 and 5, showing the telescopicdrill stem section as further collapsed, causing a higher back pressureof mud laden fluid to be built up above the telescopic drill stemsection, and causing a red danger light to be displayed to the driller,indicating to him that the drill bit is still not entering the earthformation as fast as the drill stem is being lowered into the well boreabove the telescopic drill stem section, and that there is danger ofadded pressure being applied to the drilling bit unless lowering ofdrill stem into the hole above the telescopic section is stopped.

Figure 7 is a view similar to Figures 4, 5 and 6 clearly showing thetelescopic drill stem section as being fully collapsed, but that theflow of mud laden fluid has not stopped its circulation therethrough.

Figure 8 is a detail in section view of the upper end of the telescopicdrill stem section, clearly showing the nozzle arrangement and thepressure controlling stem thereof.

Figure 9 is a detail in perspective of one portion of the outer memberof the telesco ic drill stem section.

igure 10 is a detail in perspective of the upper end of the inner memberof the telesco ic drill stem section.

igure 11 is an enlarged sectional view of the telescopic drill stemsection taken on line 1111 of Figure 8.

Figure 12 is an enlarged sectional view of the telesco ic drill stemsection, taken on line 12-12 of igure 5.

Figure 13 is an enlarged sectional view of the telescopic drill stemsection, taken on line 1313 of Figure 6.

Figure 14 is an enlarged sectional View of the telescopic drill stemsection," taken on line 1414 of Figure 7 F igure-15 is a detail, in sideelevation, of the brake actuating mechanism.

Figure 16 is a front elevation of the electric signal device.

Figure 17 is a view partly in sectional elevation and partly in sideelevation of the electric signal device.

Figure 18 is a detail of the manually actuated switch member of theelectric signal device.

Figure 19 is a view taken of F igure 17.

Figure 20 is a view taken on line 2020 of Figure 17.

on line 1919 As intimated above, our invention resides in the provisionof means, first, to permit the drilling bit to progress in depth throughhard earth formation, a predetermined distance, with a predetermineddrill stem pressure on the drilling bit, or cones; second, in theprovision of means to display a safety signal, preferably a green light,during the period of time that drilling is normal, and that upper drillstem being lowered by a cable, is approximately in the same speedrelation as to the progress made by the drilling cones; third, todisplay a warning signal when the telescopic drill stem section hascollapsed or shortened the lowering of drill to a predetermined length;fourth, to display a danger signal when the telescopic drill stemsection has collapsed to a predetermined shorter length; fifth, tolightly actuate a brake mechanism when the warning signal is displayed,and sixth, to fully set the brake actuating mechanism when the dangersignal is displayed to stop further lowering of upper drill stem untilthe bit has progressed sufliciently to lengthen out the telescopic drillstem section.

It should be borne in mind, that our primary aim is, at all times, tomaintain a predetermined pressure, by weight of a lower section of drillstem on the bit, and no more, to display a safety signal during theperiod of normal drilling, to display a warning signal when thetelescopic drill stem section has collapsed to a predetermined length,to display a danger signal when the drill stem has been collapsed to apredetermined shorter length, and to actuate a brake mechanism, first,but lightly when the warning signal is displayed and to fully set thebrake actuating mechanism with the display of the danger signal.

First,.we shall describe part of the usual drilling apparatus, withwhich our invention is used for eflicient rotary deep oil well drilling.

In the drawings, preferably Figure 1, we have illustrated the greaterpart of a deep well rotary drilling apparatus which consists, as shown,of the usual derrick A, including the sills and the floor, the rotarytable B, the surface casing C, the cable drum D, the cable E, whichrides over suitable crown pulleys F, a traveling block G having sheavesover which the cable rides and which supports the weight of an uppersection of connected drill stems designated H. The connections betweenthe upper drill stem section H and the traveling block G being a hook I,a swivel member J, and a bail connection K. It also includes a mud ladenfluid hose L having connection at one end with the swivel member J andits opposite end with a mud laden fluid conducting pipe M, which hasconnection at one end with the usual mud pump N. A steam boilerdesignated 0 also forms a I as part of the usual well drilling apparatusand from which extends the steam conducting pipe P. It may be added thatthe cable drum is provided also with the usual brake band connected atone end to the floor of the derrick A. The reference character Sdesignates the usual Kelly joint employed with well drilling apparatus,and the reference character T designates the mud fluid pressure gaugewhlch gives the reading of pressure that the mud laden fluid is beingpumped into mud pipeM and through the drill stem line, as will be morefully set out hereinafter. In carrying out the aim of our presentinventlon, We employ, in connection with the drilling apparatusdescribed, what we term a drill stem line length compensator designatedgenerally in Figure 1 as U, which is suitably connected at its upper endto the lower end of the upper drill stem section H; a lower drill stemsection of predetermined length and designated generally in Figure 1 asV; an electric signal device designated generally in Figure 1, as W anda brake setting and releasing mechanism designated generally in Figure2, as X.

We shall now describe what we have herein ly the length of theusualdrill stem section.

A suitable semi-circular metallic facing memher 2, acting as a key orrib, is either formed integrally with the bore of the tubular member 1,or suitably welded to the inner wall of the tubular member 1, and itextends from a point near the top thereof, to a point near the lower endthereof, as clearly shown in Figure 3. The tubular member 1 is providednear its lower end with a fixed internal ring 3 acting as a stop. 4 v

The lower end of the tubular member 1 is internally screwthreaded, as at4, andreceivable in this lower screwthreaded end of the tubular member.1, is an externally screwthreaded gland 5, between the inner end ofwhich, and'the lower end of the fixed stop rin '3, a suitable packing6-isdisposed.

Telescopically connected with the outer tubular member 1 of the lengthcompensator, is a suitable inner'and lower tubular member 7. Telescopicmember'7 is provided at its upper end with an outer semi-circularmetallic facing designated 8, the side edges of which have longitudinalsliding engagement with the longitudinal side edges of the internalfacing member 2 of the outer tubular member 7,'which internal structureof the two tubular telescopic, members prevents rotary movement ofeither member relative to the other, but permits longitudinal telescopicmovement of the two members relative to each other, the purpose of whichis to permit the length compensator to be shortened and lengthened, aswillbe more clearly understood hereinafter. The upper edge of theinternal ring 3 acts as a stop for the lower edge of the segmental outerfacing 8 of the tubular member 7 to engage for limiting extensionmovement of the two telescopic members. The inner tubular member 7passes downwardly through the aforesaid packing and the gland, asclearly shown in Figure 3. The packin 6 prevents possible leakage of mudladen uid carried inthe drill stem line from passing between the tubulartele-' scopic members and by passing-into the return fluid and cuttingssurrounding the drill stem line.

The upper end of the outer telescopic member 1 is internallyscrewthreaded, as at 9, for receiving the externally screwthreadedportion 10 of a nozzle head 11. The nozzle head 11 depends into theouter telescopic member 1 a suitable distance, and extending downwardlyfrom the nozzle head 11, is a mud laden fluid pressure controlling stem12. The stem 12 is-straight and of uniform diameter for a predetermineddistance of its length, and from there on to the lower end thereof, itis gradually tapered, as at 13.

The nozzle head 11 is provided with the passage 14 which communicates atits lower end with a plurality of laterally directed nozzle, ordischarge openings 15 formed in the" upper end of the pressurecontrolling stem 12. The nozzle openings 15 have inclined wall sections16 for directing mud laden fluid downwardly and outwardly therefrom intothe outer tubular telescopic member 1. A plurality of channeled mudladen fluid conducting grooves 17 are formed on the face of the stem 12.These grooves run longitudinally of the pressure controlling stem 12,and the upper ends thereof communicate with the nozzle openings 15. Thelower ends of the fluid conducting grooves 17 terminate in the face ofthe tapered section 13 of the stem by fading out. .The grooves 17 arepreferably.

although not necessarily, parallel with oneanother.

When the telescopic drill stem section V is in its furthermost extendedposition, the point of the mud laden fluid pressure controlling stem isa considerable distance from entranc into the upper end -'of theinnertelescopic drill stem member 7, which distance is determined by thelength of the device. Whatever this distance may be, is the distance thedrilling bit Y can penetrate or cut into thei earth formation before anyback pressure of the mud laden fluid is built up, greater than thenormal working head pressure. Just as soon as the outer telescopicmember 1 has telescoped the inner telescopic member 7 sufiiciently tocause the tapered end 13 of the stem 12 to enter the upper end of theinner telescopic member 7, back pressure of the mud laden fluid willstart to build up and as the stem continues to enter member 7, the fluidgradually builds up greater back pressure from the telescopic drill stemsection U to the mud pump N, but at no time is the circulation of themud laden fluid completely stopped, as the stem groove 17.will alwayspermit a quantity of mud laden fluid to continue to flow through thelength compensating device U. Also, when fully collapsed, there s asmall clearance space between the straight stem section 12 and the innerwall of the inner telescopic member 7. It is important that the flow ofmud laden fluid should not be stopped altogether for the reason such agreat back pressure may be developed as to the break the hose L, orinjure the mud pump.

lVe shall .now describe the hydraulically operated signal, which isautomatically operated by the telescopic movements of the lengthcompensator U connected in the drill stem line.

The electric signal comprises, in part, a Bourdon gauge housed in acasing 78, and the gauge consists of a casing 19 provided with agraduated pressure indicating dial 20, a closed curved elastic tube 21,the free, or closed end of which actuates a registering pointer 22 fixedto a shaft 23. The pointer 22 is actuated through the medium of a link24 suitably connected to the free end of the elastic tube 21 andpivotally connected at its opposite end to the outer end of an arm 25pivoted, as at 26. Arm 25 is provided at its inner end with a pluralityof gear teeth 27 engaging a pinion gear 28 carried by the pointer shaft23. The open end of the elastic tube 21 has connection with an orificedcoupling 29 which coupling is also connected with a suitable pipe 30leading to the lower end of a fluid container 31. The fluid container 31is connected through the medium of a suitable pipe connection 32 havinga restricted orifice 33 with the mud laden fluid conducting pipe M,which connects the mud pump N with the swivel joint J at the upper endof the upper section of drill stem. The signal casing 18 is fixed to asuitable post, or support 34 separated from the derrick A so as toarrest as much as possible vibrations imparted to the electric signaldevice.

Position in advance of the Bourdon gauge case 19 is a suitable manuallyactuated fiber switch member which is rotatably supported on a shaft 36in axial alignment with and in advance of the pointer shaft 23. The

fiber switch member 35 is provided with a suitable operating handle 38which passes through an opening 39 in case 18 and which is provided witha pointer 40 to register with a selected reading of a graduated pressuredial 41 fixed to the electric signal case 18, and which pressure readingcorresponds to the pressure readings of the dial of the Bourdon gaulgeand the pressure readings of the switch The opposite face of the switchmember 35 is provided near its edge, in arcuate aligned position, withthree electric contact terminals designated 42, 43 and 44, which to thedriller represent a safety light zone, a warning light zone and dangerlight zone, respectively. The warning contact terminal 43 is relativelyshorter in length than the safety contact terminal 42 and the dangercontact terminal 44, and the warning contact terminal is interposedbetween the other two contact terminals, but insulated therefrom, as at45.

Leading from each of the switch contact terminals 42, 43 and. 44 arethree conductors 46, 47 and 48 respectively. These conductors lead,respectively, to three electric lamps designated 49, 50 and 51 which aresupported by a partition 52 in suitable spaced relation, at the forwardend of the signal casing 18 and behind a plurality of lenses designated53, 54 and 55, respectively, and each conductor is connected with aconductor 56 leading to one side of a source of electrical supply.

The pointer 22 is provided to one side thereof and movable with thepointer and its shaft, with a suitable resilient yielding brush 57,which is connected with an electrical conductor 58 leading to theopposite side of the source of electrical supply, which may be a battery59, or any other suitable source of supply.

\Vhen the pointer brush engages the switch plate contact terminal 42,the green light will be displayed, when the pointer brush 57 engages theswitch plate contact terminal 43, the yellow light will be displayed,and when the pointer brush engages the switch plate contact terminal 44,the red light will be displayed.

Thus, for instance, the lamp 49 is connected into what is known hereinas the safety circuit controlling a green light. The lamp 50 isconnected into what is known herein as a warning circuit controlling theyellow light and the lamp 51 is connected into what is known herein asthe danger circuit controlling the red light.

We shall now describe what we term the hydraulic brake actuatingmechanism, which is also operated by the telescopic movements of thelength compensator U connected into the drill stem line.

As shown in detail in Figure 15, the cable drum brake actuatingmechanism embodies a brake setting lever 60, which can be manuallyneeasae actuated through the handle 61, when so de sired, instead ofbeing automatically actuated hydraulically, as will be apparenthereinafter.

The brake lever 60 is fixed at its lower end to a rock shaft having acrank 62, which rock shaft is journaled in suitable bearings 63" intobraking contact with the cable drum D when so desired with any degree offrictional 1 contact when manually operating the brake lever bymanipulating the handle thereof for leading 0d cable from the cabledrum, at any desired speed for lowering upper drill stem section intothe well hole bored by the drilling bit.

The means for automatically actuating the brake lever comprises a steamcylinder 67 pivotally supported as at 68 to the floor of the derrick A.The steam chamber 69 of the cylinder is provided with piston 70connected to the lower end of a piston rod 71, which leads upwardlythrough the upper end of the cylinder. The upper end of the piston ispivotally connected by a removable pin 72 to an arm 7 3, which arm ispivotally connected, as at 74, to acoupling 75, suitably clamped to thebrake lever 60.

A suitable inclined leg 76 is fixed to, and directed upwardly at anangle toward the longitudinal axis of the lever 60, and is provided witha channeled foot 77 adapted for slidmg contact with the brake lever 60above the clamp coupling 75. The lever arm 73 1S movable in an arcuatepatch by means of the piston rod 71. Connected at one end with steamchest69 of the steam cylinder 67, is a series of swivelly connectedsteam inlet. pipes designated generally as v79, which are connected atthe outlet ends thereof to a valve Case 80 and with which case is alsoconnected a steam pipe 81, which is a branch connection from the steampipe P leading from the steam boiler O. A mud laden fluid carrying pipe82, which is a branch from the mud laden fluid conducting pipe M, isalso connected with the valve case 83. The valve case 80 is providedwith a suitable slidable valve 84: which when the mud pump pressure isnormal for safe drilling, the mud pressure against one end of theslidable valve 84 allows the valve to open only sufliciently against asuitable spring 85 to permit steam to pass through valve groove 86 toset the brake with such tension as to allow the cable drum to revolve ata speed to lower 11 per drill steam at a predetermined speed an if forany reason the mud ladenafluid pressure increases from normal, due tothe collapsible telescopic action of the drill stem length compensatorU, the valve will be opened suficiently to admit more steam into thesteam cylinder for quickly raising the piston therein to move the brakelever 60 to quickly set the brake against the cable drum to preventfurther lowering if the upper drill stem sectioninto the well ole.

Thesliding valve action is automatic as to both the mud laden fluidpressure and the steam, thus the setting of the brake is automaticrelative to the amount of back pressure developed in the upper drillstem section by the telescopic action of the length compensator lU.

When the compensator device U is fully extended, or even collapsed up tothe point that the free end of the pressure control 12 is just about toenter the upper end of the inner telescopic member 7, the normal workingpressure of the mud laden fluid, which we will say for the purpose ofillustration only is five hundred pounds, is present, and the greenlight of the signal will be displayed and the steam and mud fluid valvewill be in such position as to admit such amount of steam into thecylinder 67 as to set the brake to permit the cable drum to revolve atsuch speed as to lower upper drill stem into the hole at a predeterminedspeed.

When the length compensator U has collapsed to a point where the taperedsection 13 of stem 12 has entered the upper end of the inner or lowertelescopic member 7 sufiicient- 1y to set up a back pressure to thepump, of

'say, for illustration only, five hundred fifty pounds by restrictingthe flow of mud laden fluid through the compensator U, the yellow lightwill be displayed and the green light will 0 out, and simultaneouslytherewith, the slldable valve 84 will be slightly moved by the increasedpressure of the mud laden fluid, allowing more steam to enter thecylinder 67 having the bleeder valve 87, to further set the brake andslow up feedmg of upper drill stem into the hole.

Now, if the drill bit continues to cut slowly, by having encounteredvery hard earth formation, and the slow lowering of upper drill stem isfaster than the progress of the bit Y, the outer telescopic member 1'will continue to move toward the lower telescopic member 7, causing thecontrol stem 12 to further enter the upper end of the lower telesco icmember, and when at such position, say or instance,

as to restrict the passage of the lower tel e 84.- will have beenfully'opened and the pressure entering the cylinder 67 and actingagainst the piston 70 will cause the brake band to be fully set againstthe cable drum, preventing the further lowering of the upper drill stemsection H until at such time as the bit will have progressed in itscutting operation sufficiently to lengthen the compensator to bring theback pressure back to five hundred and fifty pounds, causing the redlight to go out and opening the caution circuit to light the yellowlight, which simultaneously caused the sliding valve to slightly close,admitting less stem to cylinder and causing a slight let up on thebraking action.

Now, if the cutting of the bit is faster than the lowering of the upperdrill stem section H, the back pressure will gradually recede, until thepressure in the compensator U and upper drill stem section is normalworking pressure, due to the stem having extracted itself from the lowertelescopic member 7 caused by lengthening of the compensator U throughthe telescopic action thereof. When normal pressure is again restored,the yellow light will go out and the safety circuit is opened, lightingthe green light, and simultaneously therewith the sliding valve 84 willbe further closed to allow normal lowering of the upper drill stemsection H.

Thus, it will be seen that at no time can the upper drill stem sectioncome into contact and rest upon the lower drill stem section to add allits weight to the drilling bit, as the brake is set before thetelescopic device has been fully collapsed. If through an accident, theupper drill stem should add its weight to the bit, the circulation ofmud fluid would not be stopped as the complete telescoping of thecompensator U will not shut ofl theflow, but would merely light the redlight and stop the lowering of further upper drill stem. The bit isintended to be entirely safe from the weight of the upper drill stem atall times so that a predetermined weight can always be applied to thebit as recommended by the manufacturers of the bit for the various earthformations.

The outer member 1 of the telescopic device U is provided with aplurality of suitably spaced peripheral wear rings designated 85.

From the foregoing description, it is evident, that we provide a Welldrilling apparatus wherein telescopic means is employed that will permitof a predetermined pressure geing applied to the drilling bit, or conesthroughout the drilling operation, wherein an electric signal device ishydraulically controlled to indicate by lights to the driller theprogress of the bit into the earth formation,

and, also wherein an automatic brake actuatlng mechanism ishydraulically controlled for lowering drill stem above the telescopicmeans into the hole in timed relation to the cutting progress made bythe drilling bit.

The many advantages of the herein described invention will readilysuggest themselves to those skilled in the art to which it appertains.

From the foregoing description, it is evident that a simple device forthis purpose has been disclosed, but it is to be understood that we donot desire to restrict, or limit ourselves to the very details of theconstruction shown and described, which is merely illustrative, it beingobvious that changes, not involving the exercise of invention, may bemade without conflicting or departing from the spirit of the inventionwithin the scope of the appended claims.

This is a division application of an application for patent filed in ournames on F ebruary 23, 1932, Serial No. 594,540.

We claim:

1. In combination with an oil drilling apparatus comprising a string ofrotar oil well drill stems through which fluid is pumped under pressureand provided with a, means for controlling vertical movement of said oildrilling apparatus, a braking mechanism cooperable with said means, saidbraking mechanism being actuated in response to ressure of the fluidpumped through the rill stems of the drilling apparatus.

,2. In combination with an oil drilling apparatus comprising a string ofrotary oil well drill stems divided into two sections through whichfluid is pumped under pressure and having a telescopic drill stemsection connecting the aforesaid two sections in a manner to permitrelative longitudinal movement between said two sections and providedwith a means for controlling vertical movement of said oil drillingapparatus, automatically actuated braking mechanism cooperable with saidmeans-for retarding the speed of downward movement of the drill sectionabove the telescopic section when said telescopic section has telescopedto a predetermined degrees.

3. In combination with anoil drilling apparatus comprising a string ofrotary oil well drill stems divided into two sections through whichfluid is pumped under pres sure and having a telescopic drill stemsection connecting the aforesaid two sections in a manner to permitrelative longitudinal movement between said two sections and providedwith a means for controlling vertical movement of said oil drillingapparatus, a braking mechanism cooperable with said means for retardingthe speed of downward movement of the drill section above the telescopicsection when a predetermined condition exists at said telescopicsection, said braking mechanism being actuated 1n response to pressureof the fluid pumped through the drill stems of the drilling apparatus.

4. In combination with an oil drilling apparatus comprising a string ofrotary oil well drill stems divided into two sections through whichfluid is pumped" under pressure and having a telescopic drill stemsection connecting the aforesaid two sections in a manner to permitrelative longitudinal movement between said two sections and providedwith a means for controlling vertical movement of said oil drillingapparatus, a braking mechanism cooperable with said means for retardingthe speed of downward movement of the drill section above the telescopicsection when a predetermined condition exists at said telescopicsection, said braking mechanism in cluding conducting means throughwhich fluid passes for actuating said braking mechanism, and meansoperable in response to pressure of the fluid pumped through the drillstems of the drilling apparatus for controlling passage of thebrake-operating fluid to the braking mechanism.

5. In combination with an oil drilling apparatus comprising a string ofrotary oil well drill stems divided into two sections through whichfluid is pumped under pressure and having a telescopic drill stemsection connecting the aforesa d two sections in a manner to permitrelative longitudinal movement between said two sections and providedwith a means for controlling vertical movement of said oil drillingapparatus, a braking mechan sm cooperable with said means for retardinthe speed of downward movement of the drill section above the telescopicsection when a predetermined condition exists at said telescopicsection. said braking mechanism includ ng conducting means through whichfluid passes for actuating said brakingmechanism, and means comprising avalve operable in response to pressure of the fluid pumped through-thedrill stems of the drilling apparatus for controlling passage I of thebrake-operating fluid to the braking mechanism.

6. In combination with an oil drilling anparatus comprising a string ofrotary oil well drill stems divided into two sections through whichfluid is pumped under pressure and having a telescopic drill stemsection connecting the aforesaid two sections in a manner to permitrelative longitudinal movement between said two sections and providedwith a meansfor controlling vertical movement of said oil drillingapparatus, a braking mechanism cooperable with said means for retardingthe speed of downward movement of the drill section above the telescopicsection when a predetermined condition exists at said telescopicsection, said braking mechanism including conducting means through whichflu d passes for actuating said braking mechanism, and means comprisinga valve in the form of a slidably arranged piston operable in responseto pressure of the fluid pumped through the drill stems of the drillingaping the speed of downward movement of the drill section above thetelescopic section when a predetermined condition exists at saidtelescopic section, said braking mechanism ineluding conducting meansthrough which fluid passes for actuating said braking mechanism, a flu dchamber forming a part of said conducting means, and a piston slidablymounted within said fluid chamber, said piston being movable in responseto'pressure of the fluid pumped through the drill stems of the drillingapparatus so as to control passage of brake-operating fluid to thebraking mechanism.

8. In combination with an oil drilling apparatus comprising a string ofrotary oil well drill stems divided into two sections through which flud is pumped under pressure and having a telescopic drill stem sectionconnecting the aforesaid two sections in a manner to permit relativelongitudinal movement'between said two sections and provided with a.means for controlling vertical move ment of said oil drilling apparatus,a braking mechanism cooperable with said means for retarding the speedof downward movement of the drill section above the telescopic'sectionwhen a predetermined condition exists at said telescopic section, saidbraking mechanism including conducting means through which fluid passesfor actuating said braking mechanism, a fluid chamber forming a part ofsaid conducting means, a piston slidably mounted within said fluidchamber, and a spring for urging said piston in one direction, saidpiston being movable in response to pressure of the fluid p mped'throughthe drill stems of the drillin apparatus so as to control passage ofbrake-operating fluid to the braking mechanism.

9. In combination with an oil drilling apparatus comprising a string ofrotary oil well drill stems divided into two sections through whichfluid is pumped under pressure and having a telescopic drill stemsection con necting the aforesaid two sections in a manner to permitrelative longitudinal movement between said two sections and providedwith.

ing the speed of downward movement of the drill section above thetelescopic section when a predetermined condition exists at saidtelescopic section, said braking mechanism including conducting meansthrough which fluid passes for actuating said braking mechanlsm, meansoperable in response to pres;

sure of the fluid pumped through the drill stems of the drillingapparatus for controlling passage of the brake-operating fluid to thebraking mechanism, and means for manually operating said brakingmechanism.

10. In combination with an oil drilling apparatus comprising a string ofrotary oil well drill stems divided into two sections through whichfluid is pumped under pressure and having a telescopic drill stemsection connecting the aforesaid two sections in a manner to permitrelative longitudinal movement between said two sections and providedwith a means for controlling vertical movement of said oil drillingapparatus; a braking mechanism cooperable with said means for retardingthe speed of downward movement of the drill section above the telescopicsection when a predetermined condition exists at said telescopicsection, said braking mechanism including conducting means through whichfluid passes for actuating said braking mechanism, means operable inresponse to pressure of the fluid pumped through the drill stems of thedrilling apparatus for controlling passage of the brakeoperating fluidto the braking mechanism, and pivoted means for manually operating saidbraking mechanism.

In testimony whereof, we have hereunto aifixed our signatures.

EDWARD J. LE COMPTE. CARTER A. HARRISSON.

